Monkey cube now expand when eaten, leading to !!FUN!!

(cherry picked from commit e3930fa79e4a02342551d006f42bb0fea1e5aefa)
Lowers caused damage to make it destroy organs rarer.

(cherry picked from commit b2b99076058a4fbc33f4adf931dede85df0eed64)
Moved same code into single organ helper to handle embedding.

(cherry picked from commit ece48ae0c477b6a5d2552995d52995153abe86e6)

Conflicts:
	code/modules/organs/organ_external.dm
Made monkey cube subtypes define what type of monkey they spawn instead of weird switch in Expand().
Rewrote belly expanding accordingly. Also now you get a living monkey from the monkey.

(cherry picked from commit 3ff6c418467963d0bcfb44e2385b41e02980c723)